Trial and Error
by usa123
Summary: If I had to see a Lullaby in Age of Ultron, this is how I would have wanted it to happen. No slash, no ships, no spoilers.


Bullets punctured the thick metal above Natasha Romanoff's head and she hunkered down behind the dumpster, ejecting the magazine from her service weapon and checking how many bullets she had left.

While the gunfire continued, she raised her hand to her mouth and shouted, "What's the status guys?"

"Almost there," Tony responded. "Just—"

Suddenly, a loud boom ripped through the air and Natasha felt the hair on the back of her neck stand on end. Knowing this was more than one of Thor's lightning storms, she lifted her .45 over the top of the dumpster and fired repeatedly in the direction of her pursuers. When her clip was empty, she sprinted backwards and threw herself through open door of a nearby (and thankfully recently evacuated) store. Once inside, she kicked the door closed and used the momentum to slide behind the long counter in the middle of the room.

"What the hell was that?" she snapped as she expelled the empty magazine, pulled a new one from her belt and slammed it into the grip of her gun.

"EMP," Clint replied in a somber tone. "Both Iron Man and Falcon were in the air. Falcon was carrying Cap."

Natasha swore under her breath. "What's their status?"

There was a painful crackling over the comms and Natasha's hand flew to her ear.

"You…us…?" Sam's voice flitted over the line, through great bursts of static.

"You're breaking up, Falcon," Clint began, but Natasha tuned him out when she thought she heard whispered voices around her. Holding her weapon at the ready, she crawled over to the leftmost side of the counter, which allowed her to see if anyone was approaching from behind the dumpster. She waited a moment but didn't see or hear any of her pursuers, so she quickly ran, almost bent in half, to the back of the store to make sure the backdoor was firmly bolted.

Now that the immediate threat had passed, she could refocus on the comms.

"'ood…'sall…'d," Steve was saying.

"No…is…not all good!" Sam shot back as the static finally died down. Tony's modifications to the comm system had finally kicked in, restoring the communications arrays that had been damaged by the EMP.

"What's your status?" Clint repeated.

"Chute deployed successfully but we were a little low for it to be useful. I'm pretty sure Cap broke his leg…"

She heard a strangled gasp in the background—most likely from Rogers—which was quickly followed by a loud four-letter expletive from Sam. "I take it back. His leg is _definitely_ broken."

"It's not that bad," Rogers responded, but his voice was tight with pain.

"Not that bad, my ass. Steve, I can literally see your shin." It must have been bad for Sam to slip and use Steve's real name over the comms. He was usually a stickler on anonymity, despite the fact that most of the Avengers' identities had been released with the Fall of SHIELD. "I'm calling it now, man: you're done."

"I can still shoot," Steve ground out, but his breath hitched in the middle of his sentence, belaying the effect his words were meant to have. "Any word...from Stark?"

Before anyone could reply, Natasha heard a clicking sound behind her and dove to the side, shoving her fingers into her ears and screwing her eyes closed as the backdoor exploded. She waited a split second for the smoke to clear before opening her eyes and firing into the doorway. She heard two cries of pain, followed by the distinctive thuds of two bodies hit the floor. Her weapon raised, she hurried over and kicked their weapons out of reach, knocking out the one man who still appeared conscious. She stuck one of their Glocks into her belt then hurried into the store bathroom, where she squirmed out of the high window and dropped stealthily into the back alley.

"—last ping was on K and 8th," Clint was saying. "I don't have a current visual." JARVIS' communications array was usually taken down during an EMP blast, so having no immediate contact with Stark wasn't unusual. However, since Steve and Sam's had flickered back to life, Tony's should have as well. Given that he hadn't checked in yet, he had either been closer to the EMP that Sam and Steve, meaning his array was permanently fried, or he was unconscious.

"I'm on it," Thor announced. As one of the only people who could lift the suit, he was responsible for moving it to safety and freeing Tony with the manual override.

By this time, Natasha had sprinted to the end of the strip mall, intending to come up behind the rest of her pursuers. She crept toward the main street, pressing herself against the left side of the building, so she would remain out of sight. After making sure there was no one to her right, she peered around the corner, spying three men in front of the building to the right of the one she had just been trapped in.

Before she could draw her weapon, she saw a red streak fly through the sky and embed itself in the dumpster. She grinned as she recognized the flashing arrow projecting from the metal siding and slid back behind the wall, once again covering her ears. Two seconds later, the dumpster exploded, and she heard loud cries of pain as the metal fragmented and embedded itself in human flesh.

As the cacophony from the explosion began to die down, an incensed roar ripped through the air.

"Banner's fine," Clint announced, answering the collectively unasked question. "He just found out he's not a fan of the EMP."

"Iron Man is unconscious, but breathing. There is no parachute in sight," Thor reported, the moment Clint had finished. After the Battle of New York, Tony had installed the safety feature in his suit and designed it to deploy in any serious drop in altitude, especially when his vitals indicated he was unconscious. Apparently it had also been disabled by the EMP. "I have sent his coordinates to evac as I do not wish to move him," Thor continued.

"Stay with him 'til evac gets there," Steve ordered, and Natasha heard the sharp rapport of gunfire over the line. She peeked around the corner of the strip mall again, having heard nothing but stifled whimpers from the other side of the dumpster for the last few moments. When she didn't see any movement, she began to cautiously walk toward the men, her weapons drawn.

"Evac's coming for you after that," Sam interjected. "You could rupture an artery—"

"With Stark down, someone has to go… _check—_ " the word came out more as a grunt than anything else "…for the scepter."

"And that someone is not going to be you."

Natasha had worked with Steve long enough to know that he was going to argue, but surprisingly, she only heard a muffled hiss of pain in response.

Concern flooded her system, but she forced it away, so she could focus on her current situation. Her emotions back in check, she crept around what was left of the dumpster and saw the three men writhing on the ground, holding various body parts, trying to stifle the bleeding.

"The frickin' elevator is down," Clint scowled into the comms. "I can climb down the outside but I think that'll take longer than we want."

"I'm on 24th and L," Natasha said, not bothering to whisper, since the men in front of her were too wounded to still be a threat. "I can be there in seven." Natasha grabbed a discarded rifle from the ground and knocked the three of them out: they could provide valuable information later, if Loki's scepter turned out to be here.

"Nah. I've got it," Sam said. "I'm closest and Thor can back me up when he's done with Iron Man."

"Of course," the demi-god replied.

"I'll cover you…'til evac gets here," Steve huffed in a resigned tone.

"That'd be great."

* * *

"There's nothing here," Sam announced ten minutes later. "Another dead end."

Clint swore over the comms. "Alright. Let's get out of here then. Everyone head to the rendezvous point. Wheels up a-sap."

His words were followed by a loud roar not far away and Natasha reflexively trained her weapon at the sound, trying to steady the shaking of her hands.

"Who's going to talk to The Other Guy?" Clint asked after a brief hesitation. It was usually Tony who irritated Hulk enough to draw his attention, then led him into an abandoned part of the town where the Hulk did his own thing, until he eventually transformed back into Banner. All Stark really had to do was keep him contained until he'd calmed down again.

They all had some familiarity with the Hulk, from the last few missions, but no one had been as successful as Stark in helping Bruce transform. Steve was usually their next best option, but he'd already been evacuated against his will. Thor and the Other Guy did not get along, despite the Asgardian's best efforts; apparently the Other Guy was still holding a grudge from their first meeting on the helicarrier. With the elevator down, it'd be a while before Clint could get there even if he rappelled down the side of the building. So it was down to her and Sam.

"I can try, if I can get a lift over there. The suit's still down," Sam said, as if reading her thoughts. Deep down though, Natasha knew that he was also too far away. Even if Thor flew him over at top speed, they'd be pushing the limits of their safety window, and that was _without_ Sam actually calming the Hulk down. Besides, Sam had only been to one previous practice session and she wasn't sure how well the Other Guy would react.

Natasha swallowed hard. "I got it," she said uncertainly.

"Nat, you don't have to—" Clint began, a worried note in his voice. She knew he was remembering the weeks after The Battle, when they had both been dealing with their respective nightmares.

She forced her voice to be steady and added a thick layer of faux bravado. "It'll be fine," she said breezily. "We'll meet you at the rendezvous point."

She sprinted down the alley before she could change her mind, following the heavy footsteps of the Hulk.

He was standing in a cul-de-sac, picking up two cars and smashing them together. Icy fear shot through her system and she had to remind herself to keep breathing.

"Hey big guy," she said. Her voice was barely audible and had cracked at the end but apparently she had been loud enough for the Hulk spun around, his gaze honing in on her in under a second.

She took a trembling breath and tried to unclench her hands, which were in tight fists at her side. "Hey," she tried again, her voice slightly steadier. "I'm not here to hurt you."

The Hulk lurched forward and she had taken five steps backwards, her hand reaching for the Glock, before she realized what she was doing.

He grunted and she made herself release the gun and raise her hands in the air, to prove her good intentions. "I don't want to hurt you," she repeated, standing her ground, though she wanted more than anything to take cover.

The Hulk stopped and cocked his head, as if waiting for her to continue.

She blinked, her mind whirring to come up with what to say next. "The sun's going down...It's time to start heading home." She winced at the cheesiness of it, but it was the first thing she'd thought of. "Don't you want to go home? Back to the Tower, I mean. Just for tonight, because Tony refuses to let you leave without making sure you've had at least one good meal and a good night's sleep. He—we—don't want a replay of what happened in Macedonia." She was positive she was rambling at this point, but she couldn't help it; all the words were escaping her at an uncontrollable rate.

The Hulk tilted his head some more, in a gesture that most closely mimicked recognition.

"You remember Tony don't you?" she continued hurriedly. "Red and gold suit? You saved his life last year, when he was falling."

The Hulk nodded and, if Natasha wasn't mistaken, he looked slightly smaller.

"Yeah, he usually does this…with you…but his suit went down."

The Hulk straightened up and roared, sending her hair whipping about her face and almost knocking her down. Suddenly, she was back on the helicarrier, thousands of feet above the air, with no place to go, trapped in a small confined space with a man she'd just met, who'd transformed into an unpredictable being, her leg caught under a heavy steel bar...

Natasha bit her lip so hard it started bleeding and forced herself back to the present, while her heart threatened to beat out of her chest. She licked her lips and swallowed a few times to coax some saliva back into her mouth.

"He's fine. He's going to be fine," she repeated, her voice now audibly trembling. "He's back on the helicarrier. Do you want to go see him? Back on the helicarrier? You'll have to calm down for that to happen though. Do you think you can do that? Can you do that for Tony?"

"To-ny," the Hulk parroted, his face contorting like the word was physically unpleasant.

"Nat." He looked straight at her and extended his hand. The movement was slow and almost gentle, but it still took everything Natasha had to not move backwards. Still, she instinctively tucked her head into her shoulder and screwed her eyes closed as he reached toward one of her raised hands.

Suddenly, rough skin pressed against her palm and she instinctively dropped to the ground and rolled away. She heard shrieking and sprang to her feet, looking around wildly for a weapon, but in her panic, she saw the Hulk stuttering toward the farthest building, beginning his transformation back into Banner.

As green hide gave way to pale skin, she dropped to her knees, burying her head in her hands and letting out a choked sob.

She'd done it. She was fine. Banner was fine.

They could go home.

She heard buzzing behind her and someone dropped to the ground next to her.

"Oh God. Nat, are you okay?" Clint asked, falling to his knees beside her and running his hand up and down her trembling back.

"I'm fine," she choked out. "We're both fine."

"I'm glad," he replied, relief evident on his face. He paused then said, "I know the timing sucks, but we have to leave. Now."

"I know." Now that the danger had passed, she felt her body begin to calm down. She rose to her feet, took a deep breath and asked, "Where's Banner?"

"Here," the physicist said, a banner advertising a law firm slung around his hips. "What happened to Tony?"

"EMP got his suit. He's unconscious but stable," Clint explained. He sprang to his feet and caught the ladder that had been thrown out of the quinjet. He motioned for Natasha to go first, but she stepped back and motioned for Banner to start. As he walked past her, she couldn't hold back her flinch, though she tried her best to mask it beneath a neck roll. She saw his expression falter ever so slightly and knew he wasn't convinced.

"Thank you," he said, stepping as far from her as possible and slowly climbing the ladder with one hand, the other clutching the banner knotted around his waist.

"You didn't have to do that," Clint muttered as he began to climb the ladder behind Banner.

As Natasha waited for him to get to the halfway point, she thought about all the times Bruce had cared for her, Clint, or the rest of the team, post-mission, on the way to the medbay, or back in the Tower, as well as all the people the Hulk had saved over the last few missions.

"Yeah," she said after a long moment. "Yeah I did."

* * *

Tony was incredibly impressed by the speed at which the Hulk had transformed and, as soon as he'd been cleared, had tried to implement everything Natasha had told him she had done. Bruce had also taken this opportunity to hold practice sessions with the other Avengers too. He would transform in the Hulk-proof room Tony had designed, and whoever he was with could use that time to become more accustomed to the Other Guy, even attempting to help him calm down if Banner wasn't able to transform back on his own volition.

Try as he might, Thor was still making no headway and reverted to Tony's original strategy of leading the Hulk into a safe zone until he calmed himself down.

Once his leg healed, Steve discovered he could usually get the Hulk to touch his outstretched hand, though he didn't immediately begin to transform, as he had done with Natasha.

With all his years of VA training under his belt, Sam was doing fairly well trying to reason with the Hulk. His transformations were the second best speed and some of the least painful, Bruce reported.

Clint was pretty hit-or-miss: sometimes he had great success helping Bruce transform, and other times not so much. In another emergency though, he'd be able to handle it.

The only one who avoided these practices like the plague was Natasha. Since they weren't team practices, no one but Bruce knew that she wasn't getting into touch with him. She thought she'd done a pretty good job of hiding her nightmares from everyone but Clint, but apparently Steve had realized what was going on, and had suggested exactly once that maybe she try it, in case it would help her conquer her fear. Natasha had shrugged and offered a marginally hopeful "maybe" in response, but never followed up on it.

* * *

A month later, she was working out in Avengers' Tower, waiting for their mission briefing at five o'clock. She was listening to her mp3 player and wailing on a punching bag in time to the beat.

Suddenly, there was a hand on her shoulder and she whirled around, her right arm drawn back to deliver a powerful blow. When she realized the intruder was Bruce, she lowered her hand.

"Sorry, Dr. Banner," she said, removing both earbuds and draping them around her neck. "Can I help you?"

Bruce fidgeted with the hem of his shirt. Then he looked directly at her and blurted, "I'm sorry, Natasha."

The spy blinked. "For what?" she asked. Bruce had never done anything to hurt or offend her. In fact, he'd been nothing but pleasant to her, even when it was obvious he was having a rough day.

"For the helicarrier." He didn't have to clarify. She immediately knew to what he was referring. "I can't imagine what that must have been like."

"You don't need to apologize, Bruce. It wasn't your choice. Loki, the scepter, Fury, they played all of us."

"That's true," Banner conceded, "but if it were as simple as all that, you wouldn't be avoiding me."

"I'm not _avoiding_ you," Natasha shot back indignantly.

Bruce shrugged. "You kinda are."

"I've just had a lot of my mind these last few weeks."

"Okay then." If Natasha wasn't mistaken, Bruce looked slightly disappointed. "If that's all…" he turned to leave.

"I just don't do well with things I can't explain," Natasha said hurriedly, before she changed her mind. "Taking down hitmen and murderers is a walk in the park. Dealing with aliens and creatures grown in labs by evil megalomaniacs…it's just a lot for me to handle. I know I'm not handling the Other Guy—you—well but it's hard for me to separate him and the rest, even when you've been nothing but nice to me."

Banner looked over his shoulder, his face cloudy with emotion. "Okay," he said dully, turning back to the door.

"I'm trying, Bruce," Natasha said, crossing her arms in front of her. "I really am. This last time just kinda…threw me for a loop."

"But it went so well," Bruce said quietly.

Natasha blinked. "It did?"

"It was the least painful of the bunch and I'm sorry because I know you're frightened of him and I hate asking you to do this, especially since I can't explain why it works. Tony and I have tried everything you did, down to the letter, but it still doesn't work like it worked with you," he trailed off and stared at his shoe, which was digging circles into the blue safety mat.

"What do you want me to do?"

"I wanted to come ask you if you'd try one more time. If it's terrible, I promise I won't ever ask you do to it again. I want to see if there's something that Tony and I are missing."

Natasha's pulse picked up and she felt her sweat freeze on her back. "I—"

"That's okay," Bruce interrupted. "It's a lot to ask, I know."

"If you really think it'll help, I'll do it," Natasha replied, trying to sound more confident than she felt.

Bruce smiled softly. "I'd really appreciate it. Does tomorrow work?"

"I actually have a briefing tonight, for my next mission."

"That's okay." Bruce was undeterred, a smile still plastered to his face. "I'll be here when you get back."

* * *

It took Natasha six weeks to finish her undercover operation and four days to recover. When she was finally back to a normal schedule, she texted Bruce and said she was ready. The physicist responded an hour later, asking if she could come by later this afternoon, around three.

She agreed.

They met on the 60th floor where Tony had installed the Hulk-proof arena, loosely based on the one SHIELD had designed for the helicarrier. This one was much larger though and was filled with things the Hulk might want to play with, to blow off some steam.

"Thanks for meeting me," Bruce greeted her as soon as she stepped out of the elevator.

"Anytime," she said shortly. She didn't mean to be so cold to him, but, despite all the progress she'd made after defecting, it was still her mechanism for dealing with things she didn't particularly enjoy.

"How did your mission go?" he asked, visibly as uncomfortable as she was.

She shook her head. "Let's not."

"Okay," he said uneasily, glancing at the screens beside the doorway. "Should we get to it then?" he asked as he motioned toward the enclosure.

"Yes," Natasha replied hurriedly.

Banner nodded and tapped a few keys on a holographic keyboard. Seconds later, the large arena door swung open and a timer began ticking.

"It's giving us thirty seconds to get in there before it closes and seals itself," Bruce explained, gesturing for her to enter. "The emergency release sequence is two-alpha-three-beta-seven-zeta-echo. Will you remember that?"

Natasha shot him an amused look, as she walked into the clear-walled arena.

"Right, of course." Banner quickly followed her as the large door began swinging closed. He waited for the ominous click before he turned to face her. "That code will open the human-sized door here," he pointed to the small door next to the large one that had just opened, "to let you out. Then, a minute later, it will gas me."

His nonchalant delivery of such a gruesome statement caught Natasha off-guard and she was unable to hide her surprised expression.

"It's not a deadly gas," Bruce assured her. "It's just a mixture of herbs and other calming scents, along with mild amounts of anesthetic that helps me—well, him—calm down. The downside is it knocks me out for a while, so it's completely useless on missions."

"Let's hope it doesn't come to that," Natasha stated as she forced a neutral expression back onto her face.

Bruce nodded before unbuttoning his shirt, folding it neatly by the door, and laying his glasses on top of it. "Are you ready?" he asked, looking her directly in the eye.

 _No_ , she thought, but she nodded anyway.

"I really appreciate this," he said as he closed his eyes and visibly relaxed.

Moments later, Natasha heard a groan and saw Banner's skin take on a green tinge. He stumbled to the other side of the room, crashing into large objects of different shapes and materials that were stacked along the way. While he transformed, Natasha stood quietly against the door, doing her best to stay calm, even though her vitals were anything but. She was ready to allow Banner to play with whatever materials he wanted before he was ready to change back, but as soon as the transformation was complete, the Hulk turned and looked directly at her.

Natasha took a deep breath and shoved her emotions into a box, locking it tightly and burying it deep inside her. She slouched slightly, taking on an unassuming posture, and raised her hands to shoulder level, doing her best to copy her actions from a month ago.

Even though she had done moved more slowly than usual, the Hulk immediately assumed a defensive posture and roared, directly at her. If she hadn't been standing next to the reinforced wall already, she would have been blown over.

"Hey big guy," Natasha said, trying and failing to keep the shake out of her voice. She took a tentative step forward, much more slowly than she had raised her arms, and exhaled silently when he didn't charge.

"The sun's about to go down. It's time to go home. You want to go home, right? Back to the Tower, where you stay so Tony can make sure you have a full meal and sleep off your transformation. You remember Tony don't you?"

The Hulk grunted and relaxed slightly, the tension in his shoulders visibly disappearing. He began walking in a circle, kicking at the felt-covered boxes in his path.

"Tony, red and gold suit, flies around on missions? He's your friend. You saved him when he was falling."

Hulk stopped moving and stared right at Natasha. "Falling bad."

"Yeah, big guy. Falling is bad." Natasha tested her luck and took another small step forward, ever so slowly extending her arm as the Hulk resumed pacing.

 _What had she said next?_ she thought frantically, her pulse ratcheting up another notch. _Oh right, something about the helicarrier._

"Tony's on the helicarrier." Natasha could hear her heartbeat pounding through the veins in her ears and was sure it was as loud as the music Tony usually played in his lab. "You want to see him, don't you? He's your friend. You're going to have to relax to do that, though."

The Hulk stilled for a brief moment.

"Tony," he growled, his voice low and gravelly.

"Yeah, Tony. Your friend, your science bro, as Clint calls you."

"Science."

"Yeah science. You're really good at it. I don't understand half of what you say, but Tony does, which means it's real and not stuff you're making up, like Clint does when he tries to fit in—"

Hulk took a step forward and reached out his hand.

"Nat."

"Yeah," she swallowed hard and remained still. "I'm Nat."

She heard him shuffle forward and instinctively closed her eyes, turning her head as she had done previously. This time though, she didn't feel his touch against her skin. She opened her eyes to see the Hulk standing with his hand out, perpendicular to the ground, hovering inches from hers.

She swallowed hard, then reached out slowly and ran her fingertips down his palm. The Hulk responded with a noise that was most similar to a mewl. Natasha repeated the gesture, then turned her hand so her palm faced the ceiling. After a moment, Hulk tilted his hand forward so his palm faced Natasha's. He began with healthy distance between them, but slowly lowered his hand until his rested against hers. There was something undeniably gentle about his touch, the way he was just barely pressing against her hand as if he was afraid he was going to hurt her.

Natasha noted all this while trying to force her lungs to keep working. When she finally coerced them into drawing another breath, she took a chance and ran her fingertips of her other hand along the back of Hulk's hand.

He jerked away suddenly, his eyes wide and the irises quickly turning brown. He spun around and hurried to the back corner, where he transformed with a muffled shriek. Natasha quickly picked up Banner's shirt and glasses, and hurried to the other side of the enclosure, where the physicist was curled into a ball, gasping for breath.

"Bruce." Natasha had never seen him like this, even after a transformation, and knelt down beside him, concern for her teammate momentarily overpowering her fear of the Other Guy. After a brief hesitation, she ran her hand up and down his back, until his shuddering breaths leveled out. Then he slowly levered himself into a sitting position, blinking owlishly. His eyes traveled around the room in an unfocused manner, as if he didn't quite have control over them yet, before finally landing on her.

"'Tasha."

She wordlessly handed him his glasses and his shirt.

"Thanks," he said drowsily. He attempted to slip back into his button-on but his hands were still trembling with the after-effects and the soft fabric slipped through his fingers.

"Here," Natasha grabbed the shirt and quickly but gently stuffed Banner's arms into it. He opted to leave the front of his shirt unbuttoned and grabbed the side of a large square cube, helping himself to his feet.

"Thanks, Natasha," he said more assertively. "I really appreciate it. That was probably one of the best yet."

"Didn't seem like it."

"It took a lot out of me, the quick changes. But it hardly hurt—I can't thank you enough."

"It was nothing," she replied mechanically, standing beside him, her hands out in case he needed assistance.

Banner shot her a look, letting her know he knew that wasn't true.

"Hopefully this will help Tony and me fine-tune the procedure."

"That's such a harsh word," Natasha interjected, before she could stop herself. She shoved back the memories of cold tables, sterile environments, dance studios, and grounded herself by focusing intently on the first thing she saw in the room, which happened to be a small green plush sphere on the ground in front of her.

"What do you propose we call it?" Bruce asked as they walked toward the other side of the arena. When they reached it, he keyed in his personal code and the smaller door swung open.

"Something softer…I don't know _what_ exactly, but not... _that_." She couldn't bring herself to say the word again, having just tamped down on the last set of flashbacks.

Banner nodded absently, looking desperately like he wanted to thank Natasha with a hug or some other sort of physical contact, but he refrained.

They stood in an awkward silence for a moment, then Natasha said, "Well, I need to go food shopping, so I'm—"

"Of course!" Bruce walked a little faster to the training room door and hurried through it, catching the handle on the other side to hold it open for her. "Sorry I kept you."

"I was glad to do it," Natasha said and it wasn't until later that night that she realized she actually meant it.

* * *

The week after that, the call to Assemble came in. It was their first assignment as a full team in almost three months and, though everyone was a bit off at first, they quickly fell back into the swing of having the entire squad there.

Hours later, when all the synthetic creatures were finally dead, Tony bobbed in front of the Hulk, egging him on until they were out of city limits. Still hovering in front of the Hulk, he retracted his gauntlet, revealing his flesh hand, which he held out, palm facing Bruce, just as Natasha had. The Hulk stopped in his tracks and stared blankly at Tony's hand, but slowly reached out to lay his palm against it. After a second, he shook his head and roared, bounding off into a local, luckily kid-free, park.

"No biggie," Tony huffed into the comms. "We'll just do it the old fashioned way." He reduced the foot thrusters and lowered himself to the ground, leaning back against a tree while Bruce explored the playground equipment.

The Hulk had just tripped on a rocking metal duck, roared loudly, and was about to rip the toy out of the ground when Natasha hurried up.

"What are you doing, Red?" Tony asked, snapping to his feet.

"I can do it," she said, clasping her hands tightly together to hide the slight quiver.

"But Natasha—"

"Someone once told me that if you start running, they'll never let you stop. Besides, he needs me." With that, she turned her back to Tony and walked slowly over to the Hulk, slowly opening her hand and holding it up.

The Hulk turned immediately and fixed her with a borderline dangerous glare.

"Hey Bruce. The sun's going down…" she began, the routine feeling almost familiar at this point. He almost visibly relaxed when he saw her, not at all like he'd reacted when he'd seen Tony, and slowly hobbled over, holding up his clenched fist then slowly uncurling his fingers. She kept talking while she ran her hand up his palm, then held out her hand flat, just as they'd done in the Tower.

"That's impressive," Tony admitted, walking up behind Natasha after Bruce hurtled off to transform. Still running high on adrenaline, she spun around at the sound of his voice, her Widows Bites clicking to life.

"Whoa there," Tony flicked on his repulsors and jetted out of her reach.

"Sorry," Natasha muttered, as she forced her breathing under control.

Tony waved his hand dismissively, then demanded, "I gotta know your secret."

"Be gentle," she said, the corner of her mouth lifting in a coy smile. "Like a lullaby."

Tony flipped up the faceplate to reveal his horrified expression. "You can't call it that."

"I can and I will," Natasha glared at him, "…if Bruce like it, that is."

"If Bruce likes what?" the physicist asked as he walked up to the two of them, looking exhausted but less worn than usual.

"Natasha wants to call this song and dance a lullaby."

"A lullaby?" Bruce's eyebrows shot into his hairline.

Natasha felt her face flush in perceived embarrassment, and shoved her hands into her pockets, turning her back to the men. "It was a stupid idea. Forget I—"

"No, no." She felt a breeze pass her shoulder and saw Bruce hurrying to cut her off. She reluctantly stopped, not willing to run her friend over…yet. "It wasn't stupid at all. It just took me by surprise. It's so… _gentle_."

"Well I said softer, didn't I?"

Bruce nodded and pulled his bottom lip through his teeth as he thought.

"A lullaby," he repeated, after a second. "I like it."

A genuine smile slipped onto Natasha's lips. "I'm glad."

She looked expectantly at Tony, expecting an argument, but the inventor just shrugged. "If it's okay with Big Green, then it's okay with me."

"Alright then. The lullaby it is."

As the last dregs of adrenaline wore off, she motioned toward the nearest intersection, where the quinjet was landing. "Come on, guys. Let's go home."

* * *

 **Thanks for reading. I'd love to know what you thought!**


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